Iraq's military spokesman says reinforcements are being rushed to the key Beiji refinery north of Baghdad amid heavy fighting there with Islamic State militants.

Brig. Gen. Saad Maan appeared on state TV on Tuesday, denying earlier reports in some Iraqi media that IS had taken over large sections of the refinery.

Ammar Hikmat, the deputy governor for Salahuddin province where the refinery is located, confirmed to The Associated Press that there is fierce fighting around the refinery and that IS militants do control part of the complex.

The government has several times said the refinery, the largest in the country, was under its control, but militants repeatedly counterattacked there in the past months.

Beiji is north of the provincial capital Tikrit, which was retaken by Iraqi forces earlier this month.